Heterosexual Anal Sex: Implications for HIV Prevention

By Jeffrey Laurence, M.D., and Rowena Johnston, Ph.D.

amfAR fellow Dr. Marjan Javanbakht

July 14, 2010—A recent analysis of several HIV transmission studies found that the risk of contracting HIV through unprotected anal intercourse is eighteen times greater than for penile-vaginal intercourse. HIV prevention messages about anal intercourse tend to focus on men who have sex with men (MSM), whose behavior in relation to anal sex has been more closely studied than that of heterosexuals. New work by amfAR fellow Dr. Marjan Javanbakht adds some significant detail to the scientific understanding of anal HIV transmission among heterosexuals, revealing that the prevalence of anal intercourse varies widely by race and ethnicity in the U.S.

Among women, African American women report the lowest rates of anal intercourse (7.9 percent) and white women report the highest (13.8 percent); while among men, rates range from 6.1 percent of Asian men to 13.5 percent of Latinos. Heterosexual anal intercourse also occurs in association with other factors that place those who practice it at particularly high risk for transmitting and acquiring HIV.

About one-third of U.S. heterosexuals report having ever engaged in anal intercourse, a proportion that has been rising since the early 1990s. The majority say they do not use condoms for anal sex, even if they do for vaginal intercourse. Earlier studies have also linked drug use to heterosexual anal intercourse. Dr. Javanbakht sought to gather more information on the characteristics as well as the risk behaviors of these men and women.

Writing in the June issue of the journal Sexually Transmitted Diseases, Dr. Javanbakht and colleagues at the University of California in Los Angeles and the Los Angeles Department of Public Health reported on more than 17,000 heterosexual men and almost 11,000 heterosexual women seen during a 20-month period in 13 public sexually transmitted disease (STD) clinics in Los Angeles County. Ten percent of both men and women reported anal intercourse with an opposite sex partner in the three months preceding their last clinic visit. (The researchers believe the true figure may be higher, given that people participating in this type of face-to-face interview tend to understate the prevalence of such sensitive behaviors.) Those who acknowledged engaging in anal intercourse were also more likely to report substance use and exchange of drugs or money for sex, and were less likely to be African American. Among white women, several sexually transmitted infections were associated with anal intercourse, particularly gonorrhea and syphilis, which were roughly four and five times more prevalent respectively among those engaging in anal intercourse.

The authors concluded that these findings “highlight the need for rectal screening recommendations [and] patient counseling messages related to condom use for AI [anal intercourse].” Their work also emphasizes the importance of developing interventions that reduce the risk of HIV acquisition for those engaging in heterosexual anal intercourse.

Dr. Laurence is amfAR’s senior scientific consultant and Dr. Johnston is vice president and director of research.